Why the Brain Gets a Boost from Exercise

Exercise is not only good for the body, but for the brain as well. Vigorous physical activity has a positive impact on brain function, mental health and mood. Now researchers from the University of California-Davis Health System have discovered one of the reasons why.

The results of their recent study show that high-intensity exercise results in increased levels of glutamate and gamma-aminobutyric acid, or GABA. These two neurotransmitters regulate the chemical messaging that occurs in the brain.

Within the brain are cells that control physical and mental wellbeing. GABA and glutamate facilitate the flow of messages between these cells. Low levels of these neurotransmitters can lead to depression and other neuropsychiatric disorders.

In a news release from UC Davis, study lead author Richard Maddock said, “Major depressive disorder is often characterized by depleted glutamate and GABA, which return to normal when mental health is restored. Our study shows that exercise activates the metabolic pathway that replenishes these neurotransmitters.”

The findings of the study, published in the Journal of Neuroscience, also provide new insights into brain metabolism. Intense physical activity causes the brain to consume large amounts of glucose and other carbohydrates. In fact, it devours more of this fuel during exercise than during other demanding activities, such as solving complex math equations or strategizing during a game of chess. The researchers now believe that the brain uses the extra energy to produce more neurotransmitters.

38 healthy volunteers participated in the study. The subjects rode on stationary bikes to reach 85% of their maximum heart rate. The research team used MRI imaging to measure GABA and glutamate levels in two areas of the brain before and after exercise. They did the same for a control group that did not exercise.

While there was no significant change in the neurotransmitter levels of the control group, the subjects who exercised showed increased levels of both glutamate and GABA. These increases occurred in two different parts of the brain: the visual cortex (where visual sensory input is processed) and the anterior cingulate cortex (which regulates heart rate, emotion and some cognitive mechanisms).

While the increased levels of glutamate and GABA appeared to diminish with time, there appear to be more enduring effects as well.

“There was a correlation between the resting levels of glutamate in the brain and how much people exercised during the preceding week,” said Maddock, who is a professor in the Department of Psychiatry and Behavioral Sciences. “It’s preliminary information, but it’s very encouraging.”

Maddock and his team hope to perform further research using brain-imaging combined with exercise to determine the impact of less intense physical activity on neurotransmitter levels. They also plan to investigate which specific types of exercise are most beneficial for those suffering from depression.